Gas turbine engines may be used to power various types of vehicles and systems, such as air or land-based vehicles. In typical gas turbine engines, compressed air generated by axial and/or radial compressors is mixed with fuel and burned, and the expanding hot combustion gases are directed along a flowpath and through a turbine nozzle having stationary turbine vanes. The gas flow deflects off of the vanes and impinges upon turbine blades of a turbine rotor. A rotatable turbine disk or wheel, from which the turbine blades extend, spins at high speeds to produce power. Gas turbine engines used in aircraft use the gas turbine aft end to produce a forward thrust. Other gas turbine engines may use the power to turn a propeller or an electrical generator.
Modem aircraft jet engines have employed cooling systems to maintain the component temperatures within acceptable limits. In the case of the turbine vanes or blades, the blades are air cooled using, for example, bleed air from a compressor section of the engine. The air may enter near the blade root, and then flow through a cooling circuit formed in the turbine blade. The cooling circuit typically consists of a series of connected passages that form serpentine paths, which increase the cooling effectiveness by extending the length of the air flow path. The air may exit through cylindrically-shaped cooling holes formed through walls of the turbine blade. In typical combustors, which include inner and/or outer combustion liners that define a chamber for the hot combustion gases, a plurality of cylindrically-shaped effusion cooling holes supply a thin layer of cooling air that insulates the hot sides of the liners from extreme combustion temperatures. The liners also include major openings, much larger than the cooling holes, for the introduction of compressed air to feed the combustion process.
Although the aforementioned cooling systems operate adequately, they may be improved. In particular, as the demand increases for more efficient engines, engine operating temperatures increase as well. However, components including cylindrically-shaped cooling holes may experience undesired oxidation, coating issues or thermally induced stresses that may degrade the effectiveness, integrity or life of the components.
Accordingly, it is desirable to have improved cooling systems that may effectively cool components that are typically subjected to elevated operating temperatures, such as those above about 704° C. In addition, it is desirable for the system to be relatively simple and inexpensive to implement. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.